types of email files

[mark lankton]

We are running CorelDraw and a 75 w Epilog. Sometimes we receive through emails files of art work to laser. JPEG files are often of poor quality. What file types do you prefer to have sent? Does vector or raster work better depending on the file? Thanks in advance for your responses.

Mark

[Mike Null]

A vector file is always better for lasering due to the fact that you have sharp edges and that it's scaleable.

An Adobe Illustrator, EPS or CorelDraw are preferred. If you must use a bitmap it should be high resolution and preferable in the size you need.

[Joe Pelonio]

Agreed on vector if at all possible.

If all they have is bitmaps try for tif. Jpgs lose resolution each time they are saved, and are compressed for fast internet speed so are the worst.

[Richard Rumancik]

For items to be cut, you definitely want a vector file.

For graphics, the advantage of a vector file is that you can scale it up or down to any arbitrary size without any loss of quality. Eventually, it needs to get turned back into a bitmap either before you plot or internal to the laser. In other words, the laser will convert a filled vector shape into a bitmap if you don't do it yourself. Often you have better control if you do it manually.

If someone sends you a logo in bitmap format, and you need to adjust it to say 85% or 115%, it will probably not look very good after resampling. But with a vector file, you can size as needed, then convert to bitmap.

You also have control of how many burns-per-inch you want to use. (I use this term because some lasers use ppi, some dpi, and some both, to express the number of burns per linear inch in x and y axes). If someone sends you a 200 dpi file but you need 300 dpi for good appearance, you may have a problem. Also, your laser has only so many possible settings available.

When people think of jpg files they usually think of low-resolution/bad file quality. This is not necessarily true. If your supplier sends a 600 dpi jpg, it may laser just fine. But web graphics are usually 72 dpi so people sometime equate jpgs with being 72 dpi and hence unsuitable. Not necessarily so.

Sending tif files as an attachment can be difficult as they are large (often multi-megabyte). A greyscale 300 or 600 dpi jpg is much smaller. For large tif files you may need to use an ftp method to transfer.

If you edit a jpg you can convert to tif first to eliminate further compression losses. Another option I use after editing is to resave as a jpg, but set the compression to zero when re-saving.

[mark lankton]

Great info as always!
Thanks for the clear answers and quick reply.
Mark

[Tom Banwell]

I use CD X3 and regularly use the trace feature to convert a raster image like a jpg or bmp into a vector image. I never engrave raster images due to the jagged edges. The X4 version is supposed to have an even better trace.

[Richard Rumancik]

Tom, I'm trying to understand what you do. If you convert a bitmap to vector using Trace, then it will convert all the black areas to closed filled vector shapes. The internal fill will still raster, correct? So it seems to me that by converting, what you are doing is providing a "smooth" vector outline and then raster filling the insides. This sounds logical, but in my experience it would be difficult to convert an image via Trace without affecting it's appearance in some way. I'm not saying it won't look good, but it may not look like the image supplied by the customer.

I did a little experiment using a bitmap of a tree. I realize that there are many parameters that can be set when doing a trace and I did not attempt to optimize in any way. Also, I admit I am not experienced with Trace.

If you were asked to engrave this tree, are you saying you would instead vector draw the outlines and raster fill them?

I have used the "outline" technique for text in some cases. That is, to improve the edge quality of larger size text I have outlined the raster text so it draws a vector outline. This smooths the edges a bit. It does not work well for small text (nor is it really needed). But I have not tried to use Trace for normal bitmaps and have not seen the need. Doesn't the conversion also increase engraving time?

[Bill Cunningham]

If the original file that you were sent was a minimum 300 dpi at the size it's needed. it should not have rough edges. It's incredibly rare for a customer to send you vector art (even rarer for them to know what it is ).When in doubt, I usually tell the customer to send something that they are happy with after printing it four times larger than they want it. That way when I reduce it four times smaller, it will only improve. The only time it doesn't is when a customer downloads some web art, and increases the res. to 300, sticks it in a .doc file, and calls it artwork If you have been in this game for a while, you begin to realize that the average customer certainly does NOT have the same critical eye that you would have when deciding what looks good. I have sheepishly handed something to a customer saying "this is the best I can do with what you gave me" and the customer says WOW it looks GREAT!! And of course, I'm thinking "are you blind"? Which all boils down to one thing, you try to do the very best you can, with the very best you can get, and hope for the very best!